Hybrid wheel and track vehicle drive system

ABSTRACT

A vehicle drive system includes a hybrid wheel and track system, having a drive wheel operably coupled to a motive source, the motive source for imparting rotational motion to the drive wheel, the drive wheel having an axis of rotation, an idler wheel displaced from the drive wheel and rotationally coupled to the drive wheel by a continuous track; and a cantilever beam supporting the idler wheel and being rotatable as desired about the drive wheel axis of rotation. A device and method for controlling a suspension are further included.

RELATED APPLICATIONS

[0001] This application is a continuation application of U.S.application Ser. No. 10/192,573 filed Jul. 9, 2002, which claimspriority from U.S. provisional application No. 60/304,213, filed Jul. 9,2001, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to vehicles, and moreparticularly to a vehicle drive system.

[0004] 2. Description of the Prior Art

[0005] There are many applications for unmanned vehicles, both inmilitary and civilian contexts. The typical scenario for the use ofunmanned vehicles is when the environment would be hazardous to humanoperators, such as an area of high radiation, intense heat or fire,smoke, dust, etc. Other hazardous conditions are found in operationssuch as searches for explosives. In still other instances, the geometryof the area in which the operation is to take place might be so small,e.g. narrow hallways or stairs, as make the use of manned vehiclesnon-feasible. In all of these situations, and many others, it isdesirable to have an unmanned vehicle that can carry various requiredpayloads.

[0006] The prior art has some examples of unmanned vehicles of the typethat are the subject of the present invention. U.S. Pat. No. 5,022,812,the “Small All Terrain Mobile Robot”, issued to Coughlan et al., on Jun.11, 1991, discloses one such example. The “All Terrain Mobile Robot”,issued to White et al., U.S. Pat. No. 4,932,831, on Jun. 12, 1990,discloses a predecessor of the Coughlan device.

[0007] Some of the limitations of the prior art are as follows:

[0008] 1. Drive wheel and idler tracks are not integrated on a commoncantilever beam

[0009] 2. Lack of independently moveable cantilever beams and tracks

[0010] 3. Lack of independently driven tracks

[0011] 4. Lack of “band track” style tracks

[0012] 5. Not designed for low acoustic, thermal, or radio frequencysignatures

[0013] 6. Not recoverable from rollover

[0014] 7. Operation is tethered vs. control using a radio link

[0015] Accordingly, the object of the present invention is to provide anunmanned, remotely controlled device that overcomes the limitationslisted above.

SUMMARY OF THE INVENTION

[0016] The present invention is an all terrain, hybrid wheel and track,unmanned ground vehicle that is remotely or automatically pilotedthrough a radio link using on board cameras, sensors, and computers. Thevehicle comprises four identical and independently driven hybridwheel/track assemblies, generally situated at the four corners of achassis. Each hybrid wheel/track assembly includes a band track segmentthat connects a large drive wheel to a smaller idler wheel that isaffixed to the end of a cantilever beam. Each cantilever beam can beindependently rotated up or down through an arc of plus or minus 90degrees about the axis of rotation of the drive wheel. The hybrid wheeland track assembly configuration disclosed herein permits the vehicle toadjust its ground clearance, to climb steep and slippery slopes, totravel over uneven and rocky terrain, to bridge ditches, and tonegotiate vertical obstacles like concrete walls, fences, andbarricades. Further, each of the cantilever beams is sufficiently longso that in the event of a rollover of the vehicle, the respective hybridwheeltrack assemblies can be individually and variously articulated soas to automatically right the vehicle. tracked segments can bearticulated so as to automatically right the vehicle.

[0017] Other unique features of the present invention include amultifuel, rotary engine that will operate at full power even while thevehicle is inverted, and a serial hybrid electric drive systemconsisting of an engine driven generator, battery storage, and in-hubelectric wheel motors. The electric drive system enables the vehicle tomove even when the engine is turned off or when the vehicle is at leastpartially submerged under water as it travels along the bottom of ariver or a lake. In addition, the four symmetrical hybrid wheel/trackassemblies are capable of skid steering and also allow the vehicle tomove in both forward and reverse directions at the same speed, whichgives the vehicle good mobility even in very confined spaces. Further,the clam-shell style body hull adapts to carry different military ofpolice payload modules, including but not limited to guns, missiles,non-lethal munitions, tear gas, vertical launch unmanned aerialvehicles, other small robotic ground vehicles, and specialized sensingand camera equipment for reconnaissance, surveillance, hazardousmaterial handling, and hostage-terrorist scenarios.

[0018] Finally, in order to dramatically increase its range and durationof missions, the vehicle is capable of positioning itself over anupright or overturned 55-gallon fuel container and refueling itselfautomatically using a specially designed probe that pierces and drawsfuel from the container.

[0019] The present invention is A vehicle drive system includes a hybridwheel and track system, having a drive wheel operably coupled to amotive source, the motive source for imparting rotational motion to thedrive wheel, the drive wheel having an axis of rotation, an idler wheeldisplaced from the drive wheel and rotationally coupled to the drivewheel by a continuous track; and a cantilever beam supporting the idlerwheel and being rotatable as desired about the drive wheel axis ofrotation. A device and method for controlling a suspension are furtherincluded.

[0020] An advantage of the present invention is that each of the fourhybrid wheel/track assemblies are independently driven.

[0021] Another advantage of the present invention is that the vehicleuses a multi-fuel engine for versatility.

[0022] A still further advantage of the present invention is that thevehicle can operate in virtually any terrain, including in limitedunderwater operations.

[0023] Yet another advantage of the present invention is that theconstraints present for manned vehicles, such as human comfort factors,survivability, toxic fume limitations, and the prohibition of underwaterand inverted operation, are either greatly reduced or completelyremoved.

[0024] These and other objects and advantages of the present inventionwill become apparent to those skilled in the art in view of thedescription of the best presently known mode of carrying out theinvention as described herein and as illustrated in the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is a perspective view of the all terrain, hybrid wheel andtrack, unmanned ground vehicle of the present invention with the upperportion of the clam-shell hull removed.

[0026]FIG. 2 shows the vehicle in a high ground clearance configuration.

[0027]FIG. 3 shows the vehicle in an underwater operation configuration.

[0028]FIG. 4 shows the vehicle in transport and road travel mode.

[0029]FIG. 5 shows the vehicle in a low ground pressure configuration.

[0030]FIG. 6 shows the vehicle in a configuration adapted for obstaclenegotiation.

[0031]FIG. 7 is a schematic view of the weapons platform electricpropulsion system.

[0032]FIGS. 8-10 illustrate the vehicle with mission-specific payloads.

[0033]FIG. 11 is a chart showing the range and fuel consumption of thevehicle versus number of days deployed.

[0034]FIG. 12 shows the acceleration loads for a 0.25 m step obstacleencountered at a travel speed of 32 km/hr.

[0035]FIG. 13 shows the acceleration loads for a 1.0 m step obstacleencountered at a travel speed of 1.6 km/hr.

DETAILED DESCRIPTION OF THE INVENTION

[0036] Referring first to FIGS. 1 and 7, the present invention is afuel-efficient, highly mobile, robotic vehicle 10 capable of extendedduration missions. The vehicle 10 is powered by a hybrid power plant 11comprising a rotary engine 12 and batteries 14. The power is transmittedto the vehicle 10 by a hybrid electric drive of the hybrid power plant11.

[0037] The hybrid multi-fuel/electric energy storage and powerconversion design 11 utilized in the present invention results insuperior fuel efficiency. The vehicle 10 uses a hybridmultifuel/electric energy storage power plant 11 as illustrated in FIG.7. Control algorithms in an on board computer keep the rotary engine 12operating at its most fuel-efficient point. The engine 12 is sized foraverage power and is supplemented by the battery pack 14 for transientpeak power requirements. The batteries 14 allow silent mobility, silentwatch, and extended operation of the vehicle 10. A generator 17 for thebattery pack 14 is powered by the engine 12.

[0038] The rotary engine 12 is both turbocharged and intercooled. It istherefore well suited for hybrid electric use because of its highefficiency (SFC 230 g/kwh to 255 g/kwh), high speed, low noise, lowvibration, and low magnetic signature. Furthermore, the engine 12 hasmultifuel capability (the ability to operate on more than one fuel,including gasoline, kerosene, or diesel fuels which may be recoveredfrom abandoned enemy vehicles or stockpiles), the ability to operate atfull power even while inverted, and excellent cold temperature startupcapability. In order to dramatically increase range and duration ofmissions, the vehicle 10 is capable of positioning itself over anupright or overturned 55-gallon fuel container and refueling itselfautomatically using a specially designed probe that pierces and drawsfuel from the container.

[0039] In the preferred embodiment, the individual batteries 14comprising the battery pack 14 are state-of-the-art, high energydensity, manganese-based batteries specifically designed for andcurrently used in consumer automotive traction applications.

[0040] The electric drive motor 16 of the vehicle 10 power fouridentical and independently driven hybrid wheel/track drive assemblies(HWTAS) 17 generally situated at the four corners of a chassis.

[0041] Drive motors 16 rotationally drive the respective large drivewheels 18 which in turn impart motion to the band tracked segments 22,which in turn impact rotational motion to the idler wheels 20. Theindividually controlled electric wheel drive motors 16 balance wheeltorque for improved traction and provide superior control andregenerative braking to capture excess kinetic energy. Each tracksegment 22 connects a large drive wheel (main road wheel) 18 to asmaller idler wheel 20 that is affixed to the end of a cantilever beam(track arm) 24. Each cantilever beam 24 can be independently rotated upor down through an arc of plus or minus 90 degrees about the axis ofrotation of the respective drive wheel 18. The hybrid wheel and trackconfiguration of each HWTAS 17 permits the vehicle 10 by rotating therespective cantilever beams 24 to adjust its ground clearance, to climbsteep and slippery slopes, to travel over uneven and rocky terrain, tobridge ditches and to negotiate vertical obstacles like concrete walls,fences, and barricades. Further, each of the cantilever beams 24 of therespective is sufficiently long so that in the event of a rollover ofthe vehicle 10, the cantilever beams 24 of the respective HWTA's 17 canbe individually articulated so as to automatically right the vehicle.

[0042] The vehicle 10 includes a variable-geometry suspension systemincorporated in each HWTA 17 that provides exceptional mobility. Theinnovative variable-geometry suspension system of the HWTA 17 comprisesa combination of three key features: sprung bogie wheels 34 on the bandtrack (track segments 22) assembly, “run-flat” pneumatic tires as themain road wheels 18, and a hydraulically-actuated swiveling suspensionarm (cantilever beam 24). The electronically-controlled suspension (ECS)32 (see FIG. 7) automatically sets suspension performance andconfiguration. The ECS 32 actuator is powered by an engine-driven ECShydraulic motor that moves and supports the arm (cantilever beam 24) sothat suspension bogie wheels 34 and track 22 are pressed to the ground.A gas-charged ECS accumulator maintains pressure on the ECS hydraulicmotor, which in turn provides spring motion to the suspension arm(cantilever beam 24). Motion damping and shock absorption are providedby an electronically-controlled ECS valve, which bypasses the highpressure side of the ECS hydraulic motor to the low-pressure side.

[0043] The ECS 32 increases or decreases suspension stiffness anddamping coefficient depending on terrain roughness and speed of vehicle10. In addition, the ECS 32 adjusts pneumatic tire pressure of drivewheel 18 on the run to modify suspension compliance. The ECS 32controller raises the track arms (cantilever beams 24) to variablepositions so that the vehicle can assume differing configurations, asnoted in relation to FIGS. 2-6 below.

[0044] Referring now to FIGS. 2-6, the track arms (cantilever beams 24)are rotatably raised to their full extension supporting the vehicle 10on the respective idler wheels 20 to maximize ground clearance for boththe rough terrain crossing and obstacle traversing mode (FIG. 2), andfor water submerged travel (FIG. 3). In the flat position (FIG. 5),resulting from vehicle 10 weight ground pressure is reduced to a minimumfor traveling on soft snow, sand, or mud. The track suspension arms 24are raised automatically for minimum drag in the pivot steer (as analternative to drag or skid steering) mode (FIG. 4) for transport andrelatively high speed traveling on roads. The ECS 32 varies the approachangle to an obstacle by raising the idler wheels 20 of the leading twoHWTA's 17 on the vehicle 10 when in obstacle negotiation mode (FIG. 6,discussed in further detail below). In addition, the four symmetricaltrack segments 22 of the respective HWTA's 17 combined with the use ofskid steering allow the vehicle 10 to move both forward and in reverseat the same speed. This capability gives the vehicle 10 good mobilityeven in very confined spaces.

[0045] The ECS 32 automatically levels the vehicle 10 on slopes oruneven ground and assists in self-recovery if the vehicle 10 tips.Hydraulic disc brakes 38 supplement the intrinsic dynamic braking of thefour drive motors 16. The disc brakes 38 also function as the parkingbrake. A small, battery 14 powered electrically-driven, auxiliaryhydraulic pump 40 is used to provide suspension, braking, and weaponsystem movement during stealth mode, when the engine 12 is not running.

[0046] In order to efficiently negotiate obstacles, the vehicle 10 usestracks 22 with an automatically controlled angle of approach as depictedin FIG. 6. The vehicle 10 is able to negotiate up to 1.1 m (44 inch)vertical obstacles, and it crosses 0.25 m (10 inch) obstacles withoutslowing down. FIG. 12 shows the vertical acceleration versus time for a0.25 m step obstacle encountered at 32 km/hr. Similarly, FIG. 13 showsthat a 1 m step obstacle can be safely negotiated at 1.6 km/hr.

[0047] The unmanned ground vehicle 10 is remotely or automaticallypiloted through a radio link using on board cameras and sensors 30 and acommon RST (reconnaissance, surveillance, and targeting) module 28. Thesensors 30 assist in detecting both positive and negative obstacles.

[0048] The combination of a wheel drive (see FIG. 4) in tandem withtrack drive (see FIGS. 5, 6) gives the unmanned ground vehicle 10 of thepresent invention unexpectedly high performance relative to prior artdevices. In addition to the unique handling characteristics describedabove, the vehicle 10 possesses outstanding endurance, capable of beingoperated continuously for 14 days over 520 km, as illustrated in FIG.11.

[0049] The vehicle 10 is also quite versatile. As shown in FIGS. 8-10,the payload carried can include many different mission-tailored weaponmodules. The clam-shell style body 46, as depicted in FIG. 10, readilyadapts to carry different military or police payload modules, includingbut not limited to guns, missiles, non-lethal munitions, tear gas,vertical launch unmanned aerial vehicles, other small robotic groundvehicles, and specialized sensing and camera equipment forreconnaissance, surveillance, hazardous material handling, andhostage/terrorist scenarios. A self-defense weapon 26 (FIG. 8) can alsobe easily included on an upper surface of the vehicle 10. Exemplaryweapons include surface-to-air missiles (Stinger or Javelin) 42,depicted in FIG. 8, and direct fire weapons (25 and 30 mm cannon) 44with a munitions compartment 48, depicted in FIG. 9.

[0050] The above disclosure is not intended as limiting. Those skilledin the art will readily observe that numerous modifications andalterations of the device may be made while retaining the teachings ofthe invention. Accordingly, the above disclosure should be construed aslimited only by the restrictions of the appended claims.

What is claimed is:
 1. A vehicle drive system, comprising: a hybridwheel and track system, having; a drive wheel operably coupled to amotive source, the motive source for imparting rotational motion to thedrive wheel, the drive wheel having an axis of rotation; an idler wheeldisplaced from the drive wheel and rotationally coupled to the drivewheel by a continuous track; and a cantilever beam supporting the idlerwheel and being rotatable as desired about the drive wheel axis ofrotation.
 2. The vehicle drive system of claim 1 being incorporated in avehicle employing a plurality of such hybrid wheel and track systems. 3.The vehicle drive system of claim 1 including bogie wheels disposedbetween the drive wheel and the idler wheel.
 4. The vehicle drive systemof claim 1, the cantilever beam being rotatably shiftable through atleast 90 degrees as desired.
 5. The vehicle drive system of claim 1, thecantilever beam being rotatably shiftable to at least selectivelypresent a portion of the track that is only supported by the idler wheelto a ground surface, to present a portion of the track that is onlysupported by the drive wheel to a ground surface, and to present aportion of the track that is supported by both the idler wheel and thedrive wheel to a ground surface.
 6. An electronically controlledsuspension system, comprising: (1) a hybrid wheel and track system,having; a drive wheel operably coupled to a motive source, the motivesource for imparting rotational motion to the drive wheel, the drivewheel having an axis of rotation; an idler wheel displaced from thedrive wheel and rotationally coupled to the drive wheel by a continuoustrack; a cantilever beam supporting the idler wheel and being rotatableas desired about the drive wheel axis of rotation; and (2) a controllerfor controlling operating parameters of the hybrid wheel and tracksystem.
 7. The electronically controlled suspension system of claim 6being incorporated in a vehicle employing a plurality of such hybridwheel and track systems.
 8. The electronically controlled suspensionsystem of claim 6, the controller being operably coupled to thecantilever beam for rotatably shifting the cantilever beam through atleast 90 degrees as desired.
 9. The electronically controlled suspensionsystem of claim 6, the controller being operably coupled to thecantilever beam for rotatably shifting the cantilever beam to at leastselectively present a portion of the track that is only supported by theidler wheel to a ground surface, to present a portion of the track thatis only supported by the drive wheel to a ground surface, and to presenta portion of the track that is supported by both the idler wheel and thedrive wheel to a ground surface.
 10. The electronically controlledsuspension system of claim 6, the controller increasing/decreasingsuspension stiffness of the hybrid wheel and track system responsive toterrain and vehicle speed.
 11. The electronically controlled suspensionsystem of claim 6, the controller adjusting tire pressure of the drivewheel as desired during operation to modify suspension compliance of thehybrid wheel and track system.
 12. The electronically controlledsuspension system of claim 6, the controller controlling the cantileverbeam to affect a vehicle ground clearance.
 13. The electronicallycontrolled suspension system of claim 6, the controller controlling thecantilever beam to affect the angle of approach of the hybrid wheel andtrack system to an obstacle.
 14. A method of controlling a suspensionsystem, comprising: providing a hybrid wheel and track system, having; adrive wheel operably coupled to a motive source, the motive source forimparting rotational motion to the drive wheel, the drive wheel havingan axis of rotation; an idler wheel displaced from the drive wheel androtationally coupled to the drive wheel by a continuous track; acantilever beam supporting the idler wheel and being rotatable asdesired about the drive wheel axis of rotation; and controllingoperating parameters of the hybrid wheel and track system system bymeans of a controller.
 15. The method of claim 14, including operablycoupling the controller to the cantilever beam and rotatably shiftingthe cantilever beam through at least 90 degrees as desired.
 16. Themethod of claim 14, including operably coupling the controller to thecantilever beam and rotatably shifting the cantilever beam to at leastselectively present a portion of the track that is only supported by theidler wheel to a ground surface, to present a portion of the track thatis only supported by the drive wheel to a ground surface, and to presenta portion of the track that is supported by both the idler wheel and thedrive wheel to a ground surface.
 17. The method of claim 14, includingincreasing/decreasing suspension stiffness of the hybrid wheel and tracksystem responsive to terrain and vehicle speed by means of thecontroller.
 18. The method of claim 14, including adjusting tirepressure of the drive wheel as desired during operation to modifysuspension compliance by means of the controller.
 19. The method ofclaim 14, including controlling the cantilever beam of the hybrid wheeland track system to affect a vehicle ground clearance by means of thecontroller.
 20. The method of claim 14, including controlling thecantilever beam of the hybrid wheel and track system to affect the angleof approach of the hybrid wheel and track system to an obstacle by meansof the controller.